This project proposes a study on the biological role of hyaluronic acid in the normal and abnormal joint. Various animal arthritis models will be studied from the point of view of changes in concentration and molecular size of hyaluronic acid. The effect of intraarticular injections of various molecular size Na-hyaluronate on the pathological process will be studied. Synovial cells from normal and arthritic joints will be cultured both in static and steady state systems, and the production of hyaluronic acid of various molecular sizes will be determine. The effect of various agents (lectins, ascorbic acid, and Na-hyaluronate of different molecular sizes) on the quantitative and qualitative aspects of hyaluronic acid synthesis will be investigated. The effect of intraarticular application of hyaluronic acid degrading agents (enzymes, ascorbic acid) on the hyaluronic acid, synovial fluid and cartilage will be studied. It is also proposed to investigate, by chemical analysis, the structure of hyaluronic acid obtained from normal and abnormal joints, in order to see if changes in the primary or secondary structure of the molecule is responsible for the changes in molecular size.